1. Field of the Invention
The present invention relates to telecommunications and, more particularly, to methods and systems for identifying mobile stations in communication with a packet-switched network.
2. Description of Related Art
In wireless telecommunications networks in North America, each mobile station has been traditionally identified by a unique 10-digit mobile identification number (MIN). The MIN typically served two identification functions. First, the MIN served as a device identifier that uniquely identified the mobile station itself. For example, wireless telecommunications networks would use the MIN transmitted by a mobile station, often in combination with an electronic serial number (ESN) and other information, to authenticate the mobile station for access to radio resources (e.g., when the mobile station attempted to originate a call) and/or other resources. Wireless networks also used MINs for mobility management. For example, wireless networks located mobile stations (e.g., to alert them of incoming telephone calls or to send SMS messages to them) based on their MINs stored in home location registers (HLRs) and visitor location registers (VLRs).
Second, the MIN corresponded to the directory number of the mobile station, i.e., to the telephone number that could be dialed to call the mobile station. Thus, from the perspective of other users, the MIN served to identify a user, not just a device. In many cases, wireless telecommunications networks also identified users by MIN. For example, wireless networks often maintained for each user a subscriber profile, keyed by MIN, that identified what services the user subscribed to. Thus, in order to determine what services a mobile station user was authorized for, wireless telecommunications networks would often use the MIN transmitted by the mobile station to retrieve the subscriber profile for that user. In addition, wireless networks often identified users by MIN for billing purposes.
MINs often had a degree of portability. In many cases, a MIN could be assigned to different devices at different times. Thus, a user could buy a new mobile station and be able to use the same MIN (and, thus, the same directory number) as before, at least if the user stayed with the same wireless service provider. However, if the user switched to a different wireless service provider, then the user would often have to switch to a new MIN and, thus, switch to a new directory number, as well. This is because MINs were traditionally allocated in blocks to particular wireless service providers.
However, the FCC has recently required wireless service providers to implement wireless local number portability (WLNP). In accordance with this FCC mandate, a user will be able to keep the same directory number when switching wireless service providers. To achieve this requirement, wireless telecommunications networks may use two identifiers, such as a mobile station identifier (MSID) and a mobile directory number (MDN), to identify each mobile station, instead of a single MIN. The MSID is a device identifier, and it need not be portable. The MDN corresponds to the directory number of the mobile station, i.e., to the telephone number that can be dialed in order to call the mobile station.
Initially, the MSID and MDN may be the same for a given mobile station. However, if the user switches wireless service providers, then the MSID and MDN for the user's mobile station may become different. Specifically, the user may keep the same MDN (because of WLNP requirements) but may be assigned a new MSID by the user's new wireless service provider because different wireless service providers may have access to different blocks of MSIDs. In this way, it may be possible for the identical number to be used as (1) an MSID for one mobile station and (2) as an MDN for another mobile station. It may also be possible for a user to have access to several mobile stations, each having the same MDN but different MSIDs. Similarly, it may be possible that different MDNs, which may correspond to different users, could be used with the same mobile station identified by a single MSID.
The possibility that a mobile station may have an MDN and MSID that are different can create difficulties. Specifically, there may be an issue regarding whether a mobile station should identify itself by MDN or MSID (or both) in a particular communication, and there may be an issue regarding which identifier a given mobile station is actually using in a particular communication. For example, while it is conventional for a mobile station to transmit its MSID to gain access to radio resources, e.g., a wireless traffic channel, access to other resources or services may be based on MDN. For example, subscriber profiles in wireless telecommunications networks may be keyed to MDNs, as the identifier more directly tied to users. In such cases, the wireless network would need the mobile station's MDN in order to determine what services the mobile station user is authorized to use. However, different mobile stations may transmit different identifiers when seeking access to a given service, i.e., some mobile station may be configured to transmit MDN while other mobile stations may be configured to transmit MSID. Still other mobile stations may be configured transmit a MIN, without being configured to recognize the potential distinction between MDN and MSID. As a result, wireless telecommunications networks may not be able to anticipate whether a given mobile station will transmit an MDN or a MSID when seeking access to a given service. Moreover, when the network receives an identifier from a mobile station, the network might be unable to determine whether the identifier is an MDN or an MSID, because MDNs and MSIDs can be identical. Accordingly, there is a need for wireless telecommunications networks to be able to identify the source (e.g., the particular mobile station or the particular user of the mobile station) of mobile station communications, despite the potential ambiguities created by WLNP requirements.